I love a good chocolate cake, and this one looks promising:
125 g (1 cup) plain flour
125 g (1 cup) self-rising flour (= 1 cup flour + 1 1/2 tsp baking powder + 1/2 tsp salt)
60 g (1/2 cup) dark cocoa powder
1/2 tsp baking soda
625 g (2 3/4 cups) sugar
450 g dark chocolate, chopped
459 g unsalted butter
125 ml (1/2 cup) buttermilk
2 tbs oil
2 tbs instant espresso coffee granules or powder
Preheat oven to 160°C (315°F) or a lower temperature as instructed for a convection oven.
Brush a deep 23 cm (8 1/2 inch) square cake pan with melted butter or oil. Line the pan with baking paper, extending at least 2 cm (4/5 inch) above the rim.
Sift the flours, cocoa and baking soda into a large bowl. Mix in the sugar and make a well in the centre. Put 250 g chocolate and 250 g butter and 185 ml (3/4 cup) water in a saucepan and melt over low heat, stirring constantly. Gradually stir this mixture into the dry ingredients using a large spoon.
Whisk together the buttermilk, oil, coffee and eggs and add to the mixture, stirring until smooth. Pour into the pan and bake for 1 hour 40 minutes, or until a skewer inserted into the centre comes out clean. Cool in the pan, the turn out onto a serving dish, upside down.
Combine the remaining chocolate and butter in a small pan and melt over low heat, stirring constantly until smooth. Cool to room temperature, stirring often, until it is thick enough to spread. Spread the icing over the cake. Allow the icing to set slightly before serving.